In general, a 3GPP evolved packet system (EPS) is a packet-optimized mobile communication system supporting faster data transmission and lower transmission delay than a conventional 3GPP mobile communication system. The 3GPP EPS allows users to receive high-speed mobile multimedia service.
The 3GPP EPS necessitates an optimized radio transmission technique, an optimized control plane signaling, and an optimized radio access network, as well as a different bearer and service control model from the conventional 3GPP mobile communication system.
In the conventional 3GPP mobile communication system, packet filtering includes uplink packet filtering performed in a terminal, and downlink packet filtering performed in a core network gateway.
Packet filtering includes parsing header information of an IP packet to detect a service data flow to which the IP packet belongs, and ultimately causing the IP packet to be mapped to a bearer corresponding to the service data flow. Packet filtering primarily uses 5-tuples of an IP packet (i.e., a source IP address, a destination IP address, a protocol identifier, a source port number, and a destination port number).
The evolved packet system supports an ‘always on’ function by a default bearer, unlike the conventional 3GPP mobile communication system. That is, when initially attempting to access a network for registration, a terminal establishes a Non-Guaranteed Bit Rate (Non-GBR) bearer as a default bearer, and performs basic IP signaling and application signaling through the established bearer, which minimizes a latency for packet transmission and a setup time for a service requiring establishment of a dedicated bearer.
In the evolved packet system, a terminal is allowed to access one or more packet data networks simultaneously, and establishes a default bearer for each packet data network. The terminal is allocated one or more prefix (or subnet)-based IP addresses from a specific packet data network to access the packet data network for packet transmission and reception.
Meanwhile, the terminal is required to establish a separate dedicated bearer to perform a more stringent quality of service, e.g., Guaranteed Bit Rate (GBR) service, than default bearer service. In general, packet filter information for identifying a service data flow mapped to the dedicated bearer corresponds to the dedicated bearer. Information for uplink packet filtering performed in the terminal is delivered as a Traffic Flow Template (TFT) from a network to the terminal at a time when a dedicated bearer and a session are established.
However, specific packet filter information is not provided for the default bearer, which is just used as a wild card. That is, a dedicated bearer corresponding to a packet is searched using the packet filter information, and when there is no corresponding dedicated bearer, the packet is decided to correspond to the default bearer.
Thus, when the terminal accesses one or more packet data networks simultaneously and an uplink packet does not correspond to a dedicated bearer, there may be several available default bearers that may correspond to the packet, because there is a default bearer established for each packet data network.
Determination of a bearer corresponding to an uplink packet which should be mapped to a default bearer requires a packet filter matching task to be performed on all dedicated bearers in advance, which may cause increasing filtering time and delayed packet transmission.